Connections in medium-voltage underground power distribution systems, such as between cables and transformers, are generally accomplished with specially designed separable male and female electrical connectors, such as loadbreak connectors and deadbreak connectors. Such cable connectors, used in conjunction with 15, 25 and 35 kV systems, generally include a power cable elbow connector and a bushing insert. The elbow connector has one end adapted for receiving a power cable and another end adapted for receiving an insertion end of the bushing insert. The opposite end of the bushing insert, which extends outward from the elbow connector, may in turn be received in a bushing well of a transformer, for example.
Such elbow connectors typically comprise a conductor surrounded by a semiconducting layer and an insulating layer, all encased in a semiconductive outer shield. The end of the elbow adapted for receiving the bushing insert generally includes a conically tapered inner surface, which mates with a conically tapered outer surface formed on the insertion end of the bushing insert. When connected with a bushing insert, the conductor encased in the elbow makes mechanical and electrical contact with a conductor encased in the bushing insert. The elbow may further include a cuff at its bushing receiving end for providing an interference fit with a molded flange on the bushing insert. This interference fit between the elbow cuff and the bushing insert provides a moisture and dust seal therebetween.
Power distribution service personnel, whose function is to monitor and control such underground power distribution systems, often need to access the cables and connectors to facilitate servicing and repairs. One of the first steps required in servicing underground cable systems is to confirm that the circuit is deenergized. This is done by directly accessing a conductor within a connector and testing the voltage with a direct test probe. The conductor is then grounded at both ends to prevent injury should the cable system become accidentally energized. Finally, the cables are removed from the switch or transformer bushings to achieve a visible break between the cables and their respective bushings.
To accomplish the above voltage testing and grounding procedures, a direct operating interface is provided in the connector system to enable direct access to the conductor. Such interface is typically in the form of a loadbreak reducing tap plug having one end inserted in an elbow T-connector and having an open opposite end providing a direct access point to a cable attached to the T-connector, as shown and described in U.S. Pat. No. 4,799,895. When the cable system is energized, the open end of the tap plug is covered with an insulating cap. When the open end is uncovered, a direct test probe can be inserted therein to test the system voltage and a grounding elbow connector can be subsequently coupled thereto to ground the system.
It is also often desirable to perform ancillary functions on the cable system without having to deenergize the system. Such functions include active voltage sensing for circuit control and voltage surge arresting for lightening protection. Conventional devices for performing such functions typically consist of a separable connector component which is insertable into an access point of an existing connector. For example, existing voltage sensing devices, such as the Elastimold K650BIP device, use a resistor or capacitor divider network encapsulated in a basic insulation plug. As such, these conventional devices “dead-end” or terminate the access point preventing direct access to the conductor without separation of the connector.
Accordingly, it would be desirable to provide a single connector component, which permits both ancillary access to the cable system, as well as direct user access for tapping, direct voltage testing, grounding and the like.